TW202104973A - Multi-modal wide-angle illumination employing a compound beam combiner - Google Patents

Abstract

Provided is an optical apparatus that includes an illumination assembly which include an extended radiation source emitting radiation with a controllable spatial distribution and telecentric condensing optics, configured to receive and project the emitted radiation with a numerical aperture exceeding 0.3 along a first optical axis onto a field and an imaging assembly that includes a sensor and objective optics configured to image the field along a second optical axis onto the sensor and also a prism combiner positioned between the field and the condensing and objective optics which is configured to combine the first and second optical axes, while reflecting at least one of the optical axes multiple times within the prism combiner.

Description

Multi-mode wide-angle illumination using compound beam combiner

The present invention relates generally to optical devices and methods, and in particular relates to luminaires.

The illuminator is used in an optical device to illuminate an object imaged by the imaging optics.

U.S. Patent Application Publication 2013/0279017 describes an optical device, which includes: a light wave transmissive substrate having two main surfaces and edges; an optical member for coupling light into the substrate by total internal reflection; and plural A partially reflective surface carried by the substrate, wherein the partially reflective surfaces are parallel to each other and not parallel to any one of the edges of the substrate, and one or more of the partially reflective surfaces are an anisotropic surface.

US Patent 6,292,214 describes a device in which a light flux from the screen of the display unit is guided by an optical system to an observation optical system. The display screen on which the image of the sample is displayed can be observed through an eyepiece lens of the observation optical system.

US Patent 8,514,385 describes a method for inspecting an object and an inspection system, wherein the system includes: at least one primary light source, which is subsequently adapted to direct at least one illumination of at least one primary light beam toward a region of an inspected object Path imaging lens; at least one secondary light source, which is subsequently adapted to guide at least one collimating component and at least one light collecting component of at least one secondary light beam toward the area; wherein at least one primary light beam and at least one secondary light beam The light beam illuminates the area so that substantially every point in one of the imaged parts of the area is illuminated within a large angle range characterized by substantially uniform intensity; a collection path including an image sensor and a beam splitter Path and a collection path imaging lens; wherein the beam splitter is positioned between the areas and between the collection path imaging lens; and wherein at least one collimating component defines a central aperture through which at least one primary light beam propagates.

US Patent Application Publication 2004/0174591 describes a microscope for including at least one observation beam path, in particular, a lighting device for a surgical microscope with an illumination system, and a lighting device for deflecting light emitted from the illumination system To an object to be observed, in particular, a deflection device on an eye to be operated, the deflection device provides illumination of one of the objects under various illumination angles relative to at least one observation beam path, wherein the deflection device includes at least part The ground serves as the two deflection elements provided by the physical beam splitter.

The embodiments of the present invention described below provide improved equipment and methods for the illumination and imaging of a field.

According to the following detailed description of the embodiments of the present invention together with the drawings, the present invention will be more fully understood, in which:

Overview In the application of optical imaging systems (for example, optical inspection of a workpiece during a manufacturing process), an illuminator is used to illuminate a field on the workpiece with optical radiation. (As used in this description and the scope of the patent application, the terms "optical radiation", "radiation" and "light" generally refer to any and all visible light, infrared and ultraviolet radiation.) The illuminated field of the workpiece is imaged by the imaging optics It is detected by a suitable sensor.

In some applications, accurate inspection requires a field with a large diagonal size within a wide illumination angle, that is, the illumination has a high numerical aperture (NA). The inspection may further require both of the following: the radiant flux (radiation intensity) per unit solid angle is uniform across the numerical aperture, and the radiant flux (irradiance) per unit area is uniform across the field.

In optical radiation measurement, the radiation intensity I and the irradiance E are defined according to the radiation flux Φ. The radiant flux Φ expresses the energy flowing in the radiation field, and one of the common units is watt (W). Define the radiation intensity I in equation (1): I=dΦ/dΩ (1) where Ω is a solid angle. One common unit of radiation intensity I is W/sr, where sr represents the steradian as a unit of a solid angle. The radiation intensity can refer to the flux emitted into a solid angle or the flux received into a solid angle. In the following description, the symbols I _EMIT and I _{RCV are} used to represent the transmitted radiation intensity and the received radiation intensity, respectively.

Define the irradiance E of the received flux Φ in equation (2): E=dΦ/dA (2) where A is the area of the received flux. One of the common units of irradiance E is W/cm ² .

An additional radiation term used in this description The emittance M of the emission flux Φ is defined by equation (3): M=dΦ/dA (3) Wherein A is the area of emission flux.

When a high degree of radiation intensity and irradiance is required in an illuminated field with a large diagonal dimension, especially when the diagonal dimension is smaller than the space between the field and the closest point of the illuminator (usually called the "working distance") Or "free working distance") is much larger, the common illuminator is limited in the numerical aperture and angular width of the optical field. On the contrary, for a high numerical aperture and large optical field, it is difficult to achieve a high radiation intensity and irradiance. When the illuminator is used as part of an imaging system, it is usually necessary to embed a beam splitter in the illumination path so that an imaging assembly can capture images of the optical field. This constraint exacerbates the difficulty of meeting the design goals of the luminaire.

The embodiments of the present invention described herein solve the problems described above by providing illuminators for use in combination with a beam splitter and an imaging assembly. The illuminators are in a large numerical aperture and a large optical field. Achieve a high degree of both radiation intensity and irradiance.

In the disclosed embodiment, a lighting assembly includes an expanded radiation source that emits radiation having a controllable spatial distribution. The condensing optics receives and focuses the emitted radiation along an optical axis with a numerical aperture (NA) exceeding 0.3 to a field with a diagonal size from 2 mm to 20 mm. The device also includes an imaging assembly, which includes a sensor and an objective optics for imaging the field onto the sensor along a second optical axis. A beam combiner, which is positioned between the field and condensing optics and the objective optics, combines the optical axes, and at the same time makes at least one of the optical axes reflect multiple times in the beam combiner.

Despite the large NA and wide field, the telecentric configuration of the disclosed lighting assembly and its accompanying translational invariance ensure highly uniform illumination of the field. For example, the illumination assembly described below can illuminate a field with an irradiance that does not vary more than 10% across the field and a received radiation intensity that does not vary more than 20% across the numerical aperture at all points in the field. Multiple reflections in the beam splitter can be useful in meeting these goals while achieving a large NA. In addition, the design of the concentrating optics and the beam combiner enables the luminaire to be constructed with a combination of a short working distance and a wide illumination field.

First Embodiment FIG. 1 is a schematic cross-sectional illustration of an optical device 10 according to an embodiment of the present invention. The device 10 includes: an illumination assembly 20 and an imaging assembly 76, which are connected to the same optical combiner 32, which combines the optical axis of the illumination and imaging assembly, as described below.

The lighting assembly 20 includes: an expanded radiation source 22, a radiation source controller 23 and a condensing optics 21. The condensing optical device 21 includes a homogenizing rod array 29, a collimating lens array 27, a focusing lens 28 and a compensation lens 30. The collimating lens array 27 includes individual collimating lenses 70, of which further details are shown in FIGS. 2 to 3 and FIG. 5. The lighting assembly 20, together with the beam combiner 32, illuminates a field 34 along a first optical axis 35.

The imaging assembly 76 includes an objective optics 77 and a sensor 79, wherein the objective optics images the field 34 onto the sensor.

The radiation source controller 23 usually includes a programmable processor programmed in software and/or firmware to perform one of the functions described herein. Alternatively or additionally, the radiation source controller 23 includes hard-wired and/or programmable hardware logic circuits that perform at least some of the functions of the controller. Although the radiation source controller 23 is shown in the figure, for the sake of simplification, as a single, monolithic functional block, in practice, the controller may include a single chip or a group of two or more chips. The interface is used to output the signal illustrated in the figure and explained in the text. The controller shown and described in the context of the subsequent embodiments has a similar structure.

In FIG. 1, the combinator 32 is only shown schematically, and further details are shown in FIG. 6. The beam combiner 32 includes a polyhedron made of a material that is transparent to radiation, and the polyhedron has an internal beam splitter layer that is partially transmissive and partially reflective so as to transmit a part of the radiation entering the beam combiner and reflect a part thereof.

The lighting scheme of the device 10 can be divided into two independent parts: non-imaging optics, which include: expanded radiation source 22 and homogenized rod array 29; and imaging optics, which include: collimator lens array 27, focusing lens 28 , Compensation lens 30 and 稜鏡 combiner 32. The function of the non-imaging optics is to mix the light of different wavelengths emitted by the source 22 and improve the light collection efficiency. One of the additional functions of non-imaging optics is to improve the angular uniformity of illumination, thus converting low-frequency heterogeneity into high-frequency heterogeneity, which can then be easily achieved by using a fine diffuser smooth. A part of the imaging optics is used to refocus the homogenized light emitted from the non-imaging optics on the field 34 with a good separation between the aperture segments, which means that each homogenizing rod 29 will only send rays To one corresponds to the lens 70. The homogenization rod and lens are explained in more detail below.

The homogenizing rod array 29 includes a homogenizing rod 24, which generally includes solid rods made of a material that is transparent to the radiation emitted by the source 22 and/or hollow rods with reflective inner walls. Each rod includes an entrance surface 25 at one end and an exit surface 26 at the other end. The cross-section of the homogenizing rod 24 is generally rectangular (for example, square) or circular, although other cross-sections may be used instead. In some cases, the profile can vary along the axis of the rod. In the depicted embodiment, for example, the linear extent of the exit surface 26 of each homogenizing rod 24 is 2.5 or 3 times larger than the entrance surface 25 thereof. Since the elongation of the light propagating in each homogenizing rod 24 is conserved, the emission angle of the light at the exit surface 26 is reduced by the same 2.5 or 3 times. (The term "emission" refers to the product of the cross-sectional area and the opposite solid angle of an optical beam.) Each homogenizing rod 24 increases the entrance into the entrance surface 25 and the exit from the exit surface 26 by means of multiple reflections in the rod. The spatial uniformity of radiation.

The extended radiation source 22 (further detailed in FIG. 4) is driven by a signal from the radiation source controller 23, and emits radiation into the homogenizing rod 24 through the incident surface 25 of the homogenizing rod. The radiation is transmitted through the homogenizing rod 24 to its exit surface 26, and the radiation is emitted from the exit surface toward the collimating lens array 27 with a uniform radiation emittance M (due to the homogenizing effect of the homogenizing rod) (see further details in FIG. 5). ).

The collimating lens array 27 receives radiation and transmits and collimates the rays that have exited from each point on the exit surface 26. For example, the ray 36 emitted from a point 38 is collimated into the ray 40 by one of the lenses 70 of the collimating lens array 27. The rays transmitted and collimated by the collimating lens array 27 are received, transmitted and focused by the focusing lens 28. All rays focused by the focusing lens 28 are received by the compensation lens 30, and are further projected to the field 34 by the compensation lens through the beam combiner 32. For example, the collimated ray 40 is focused by the focusing lens 28 into a ray 42 focused on a point 43 on the field 34.

The collimating lens array 27 forms a diaphragm of the illumination assembly 20, wherein each collimating lens 70 includes a segment of the diaphragm. When the collimating lens array 27 is located in the focal plane of the combination of the focusing lens 28 and the compensation lens 30, the image seen from the field 34 is located at infinity (meaning that the exit pupil of the condensing optics 21 is effectively at infinity Place). This configuration with one of the exit pupils at infinity is called the "telecentric configuration". Therefore, the condensing optics 21 provides a telecentric illumination to the field 34, and the entire angle of self-field observation covers the constant translation across the field.

Regarding the irradiance E (spatial coverage) on the field 34, the exit surface 26 of each homogenization rod 24 is imaged into the field by the collimator lens array 27 and the focusing lens 28, so that the images of all exit surfaces 26 overlap in the field . The function of the compensation lens 30 is to improve the image quality by reducing the optical aberration of the illumination assembly 20. For example, the compensation lens 30 may have a meniscus shape for compensating the spherical aberration of the optical device. The uniformity of the radiation emittance M of each exit surface 26 produces a uniform irradiance E on the field 34.

As will be described in detail in FIG. 2, for the received radiation intensity I _RCV (angle coverage) on the field 34, radiation from a given exit surface 26 fills a portion of the total aperture of the illumination assembly 20. The collimating lens array 27 (detailed in Fig. 5) fills the numerical aperture of the illumination assembly so that there is no gap between the radiation from adjacent exit surfaces 26, thus generating a substantially uniform received radiation intensity I within the numerical aperture of the illumination _RCV . In addition, due to the telecentricity of the illumination as indicated above, the entire angle of the illumination observed from the field 34 covers the same translation across the field. This property is particularly useful in implementing the multi-modal functionality of the lighting assembly 20, thereby providing both bright-field and dark-field illumination, for example, as explained more fully below.

Based on the inventor’s simulations, the disclosed embodiment enables to illuminate the field 34 with a numerical aperture (NA) exceeding 0.3 in a field with a diagonal size from 2 mm to 20 mm, with a cross-field variation not exceeding An irradiance of 10% and a radiant intensity of no more than 20% across the numerical aperture at all points in the field. In some embodiments, the high-level uniformity and wide field angle are achieved with NA exceeding 0.5, or even exceeding 0.75.

In an alternative embodiment (further detailed in FIG. 3), each exit surface 26 includes a field lens 406 and a diffuser 420 for further controlling the irradiance E and the received radiation intensity I _{RCV on the field 34} Uniformity.

FIG. 2 is a schematic cross-sectional illustration showing a detail 303 of a part of the optical path in the optical device 10 according to an embodiment of the present invention. The illustration demonstrates the effect of the telecentric design of the concentrating optics 21.

The detail 303 includes the following parts from the optical device 10: the exit surface 26 of one of the homogenizing rods 24, the collimating lens 70 (from the collimating lens array) positioned opposite the exit surface 26 along a third optical axis 301 27). The focusing lens 28 and the field 34 along the first optical axis 35. The distance between the collimating lens 70 and the exit surface 26 is f _COLL , where f _COLL represents the effective focal length of the collimating lens.

As shown in FIG. 1, the illumination is telecentric because the collimator lens 70 is located in the focal plane of the combination of the focusing lens 28 and the compensation lens 30. For the sake of clarity, the compensation lens 30 and the combinator 32 have been omitted from the details 303.

The rays 302a, 302b, and 302c are emitted at a point 300 at the center of the exit surface 26, where the central ray 302b coincides with the third optical axis 301 and passes through a point 320 at the intersection between the collimator lens 70 and the second optical axis . (The lenses 70 and 28 are treated as thin lenses.) The rays 302a and 302c are the limiting rays from a ray cone of the point 300 positioned symmetrically around the central ray 302b. (The term "ray cone" is used to refer to a group of rays emitted from or incident on a point. The angular extent of a ray cone is indicated by its numerical aperture.) The collimating lens 70 collimates the rays 302a, 302b, and 302c, respectively The straight rays 304a, 304b, and 304c are then focused by the focusing lens 28 into rays 306a, 306b, and 306c so as to be focused to a point 308 on the field 34 at the intersection point of the field and the first optical axis 35.

The rays 312a, 312b, and 312c are emitted at a point 310 at the edge of the exit surface 26, wherein the center ray 312b passes through the point 320 on the collimator lens 70. The rays 312a and 312c are the limit rays of the ray cone from the point 310 positioned symmetrically around the central ray 312b. The rays 312a, 312b, and 312c are collimated by the collimator lens 70 into rays 314a, 314b, and 314c, respectively. The rays are then focused by the focusing lens 28 into rays 316a, 316b, and 316c to focus on a point 318 on the field 34.

Both rays 304b and 314b pass through a point 320 on the collimating lens 70. Since the collimating lens 70 including the point 320 is located at a focal plane of the focusing lens 28, the focusing lens refracts the rays 304b and 314b from the point 320 so that the resulting refracted rays 306b and 316b are parallel to each other. Due to the parallelism of the central rays 306b and 316b of the two ray cones (one ray cone includes rays 306a to 306c and the other ray cone includes rays 316a to 316c), and the limit rays surround their respective centers in the entire optical path The fact that the rays are symmetrical, the two cones in the field 34 are at two separate field points 308 and 318 and extend around the first optical axis 35 within the same numerical aperture. Therefore, the numerical aperture of the illumination is invariant to translation due to the telecentric design of the condensing optics 21.

The angular uniformity of the received radiation intensity at the point 308 within the cone including the rays 306a to 306c is determined from the angular uniformity of the emitted radiation intensity I _EMIT at the point 300 on the exit surface 26. Similarly, the angular uniformity of the received radiation intensity at point 318 within the cone including rays 316a to 316c is determined by the angular uniformity of the emitted radiation intensity I _EMIT at point 310.

Therefore, the numerical aperture of the radiation cone irradiated on the field 34 is determined by the width and lateral position of the collimator lens 70 in the collimator lens array 27, and the numerical aperture is invariant in translation across the field 34. In addition, the uniformity of the received radiation intensity over the field 34 within the numerical aperture is determined by the uniformity of the emitted radiation intensity from the exit surface 26.

Each point in the field 34 receives radiation from a corresponding point in the exit surface 26 of each homogenizing rod 24. Thus, for example, point 308 receives radiation from a central point on each exit surface 26, and point 318 receives radiation from an edge point on each exit surface. Therefore, the irradiance E on the field 34 is an averaged irradiance M of all the homogenizing rods 24, thereby contributing to a high degree of irradiance uniformity.

FIG. 3 is a schematic cross-sectional illustration of a detail 400 of another part of the optical path according to an alternative embodiment of the present invention, illustrating the addition of a plano-convex field lens 406. This detail can be used in the device 10 instead of the detail 303 (Figure 2).

The detail 400 includes the following parts: an array 401 of emitters 54 within the extended radiation source 22 (as will be described in detail in FIG. 4), a homogenizing rod 24 with an entrance surface 25 and an exit surface 26, and a third optical The collimating lens 70 with the axis 301 opposite to the exit surface 26, the focusing lens 28 along the first optical axis 35 and the field 34. The field lens 406 is positioned to be in contact with or close to the exit surface 26, wherein the flat surface of the plano-convex shape is extremely suitable for cementing the field lens to the exit surface.

(4)A ray 410 is emitted from the group 54 and reflected as a ray 412 by a side wall of the homogenizing rod 24. Due to reflection, a virtual source 402a is formed as an image of the group 54. The position of the virtual source 402a is found by extending the ray 412 shown as a dashed line 414 to a surface 416. Since the ray is folded by the sidewall of the homogenizing rod 24, the surface 416 is generally a curved surface. The homogenizing rod 24 reflects the rays emitted from the group 54 multiple times to generate an additional virtual source 402, thereby forming a virtual extended source 404 together. For a solid homogenizing rod 24, according to equation (4), the maximum lateral width W of the source 404 is given by: the length L of the rod, the ratio M between the linear dimensions of the exit surface 26 and the entrance surface 25, and The refractive index of the material n:

(4)

The gap between adjacent virtual sources 402 decreases as the number of reflections in the homogenizing rod 24 increases. However, due to the limited length L, these gaps do not completely disappear.

The field lens 406 images the expanded virtual source 404 onto the collimating lens 70 as an image 408, so the collimating lens is filled with the image, and finally the numerical aperture of the illumination incident on the field 34 from the collimating lens is filled. Since the illumination is imaged into the aperture stop of the illuminator (collimator lens 70), the illumination system is of Köhler-type.

The diffuser 420 (usually a weak diffuser with a diffusion angle of, for example, 5 degrees) can be placed on the side closer to the collimating lens 70 against the field lens 406 in order to improve the self-collimating lens output The angular uniformity of the radiation, and finally the uniformity of the irradiance E in the field 34 is improved.

The typical materials and dimensions of the optical components of the embodiments disclosed in FIGS. 1 to 3 are given in Table 1 below. Table 1: Typical materials and dimensions Component material Dimensions (in mm) Homogenizing rod 24 PMMA or BK7 Incident surface 25: 3×4.5 Exit surface 26: 7.5×11.25 Length: 100 Field lens 406 PMMA or BK7 Diameter: 14 Center Thickness: 4 Focal Length: 35 Collimating lens 70 Molded PMMA Focal length: 60 Focus lens 28 Molded PMMA Focal length: 80 Diameter: 150 Compensation lens 30 BK7 Convex radius: 39.8 Concave radius: 104 Center thickness: 7 Diameter: 50 稜鏡 Combiner 32 BK7 Thickness: 17.5 Outer angle: 60˚, 30˚, 90˚

FIG. 4 is a schematic front view illustration of an expanded radiation source 22 used in the lighting assembly 20 according to an embodiment of the present invention. In addition to a circular central cell 52, the expanded radiation source 22 includes a truncated sector-shaped cell 50. The homogenization rod 24 is configured such that there is exactly one homogenization rod, with its entrance surface 25 facing each cell of the expanded radiation source 22.

Each cell of the expanded radiation source 22 includes a group of emitters 54 that emit radiation toward a homogenizing rod 24 facing the other cell. One of the groups of emitters 54 is enlarged. Illustration 56 details how each group of emitters 54 includes _{three emitters 58 that emit radiation at a wavelength λ 1 and those that} emit radiation at a different wavelength λ ₂ Three transmitters 60. The emitters 58 and 60 include solid-state emitters, for example, light-emitting diodes (LEDs), such as the red LED c41-A60 from OSRAM GmbH (Marcel-Breuer-Straße 6, 80807 München, Germany), and from CREE Inc., (4600 Silicon Drive, Durham, North Carolina 27703, USA) one of the blue LED EZ 1350. Alternatively, the emitters 58 and 60 can emit radiation in the overlapping spectral ranges. In a further alternative, the emitters 58 and 60 may include so-called white LEDs that emit broadband radiation extending across the visible spectrum, such as those available from CREE Inc. Alternatively, the emitters 58 and 60 can emit radiation in the infrared (IR) or ultraviolet (UV) portion of the electromagnetic spectrum. The emitters 58 and 60 preferably include LED dies placed in close proximity to each other. The purpose of placing the emitters 58 and 60 in close proximity is to achieve both high optical power injected into the rod 24 and improved uniformity of illumination. Each of the transmitters 58 and 60 in each group 54 can be independently activated by the radiation source controller 23. Therefore, the illuminating assembly 20 can illuminate only the part of the numerical aperture, such as, for example, dark field illumination or only the right or left side, and the illumination can be controlled by enabling separate or simultaneous illumination _{with different wavelengths λ 1} and λ ₂ The spectral content.

In an alternative embodiment, for example, each group 54 of emitters may include three, four, five, or six emitters emitting at different wavelengths. By independently stimulating these emitters, the spectral content of the illumination can be controlled to include any combination of available wavelengths.

FIG. 5 is a schematic front diagram illustration of one of the collimator lens arrays 27 in the illumination assembly 20 according to an embodiment of the present invention. In addition to a circular central lens 72, the collimator lens array 27 includes—similar to the expanded radiation source 22—a lens 70 in the shape of a truncated sector. Alternatively, lenses 70 and 72 of other shapes can be used. The collimator lens array 27 is designed so that each lens of the array receives radiation emitted from the exit surface 26 of exactly one of the homogenizing rods 24. Each lens of the collimator lens array 27 includes a Fresnel lens, in which the lenses are butted together, thus promoting a uniform received radiation intensity I _RCV of the illumination on the field 34, that is, in each Substantially no gap is formed between the part of the numerical aperture guided by the Renaissance lens segment 70. In particular, the beam combination design of the disclosed embodiment makes it possible to combine the axial portion of the full illumination numerical aperture and its surrounding or circumferential portion to achieve uniform and substantially gapless illumination. In alternative embodiments, lenses other than Freinel lenses may be used, such as lenses with spherical or aspherical surfaces, or any combination of the above.

FIG. 6 is a schematic cross-sectional diagram illustrating the combination device 32 of FIG. 1 together with an imaging assembly 76 according to an embodiment of the present invention. The beam combiner 32 includes an upper beam 80 and a lower beam 82 connected by a beam splitter layer 84. The combiner 32 further includes a first surface 90, a second surface 94 and a third surface 102. The objective optics 77 of the imaging assembly 76 images the field 34 onto the sensor 79 along a second optical axis 78, for example, with an optical numerical aperture between, for example, 0.1 and 0.3. The first optical axis 35 and the second optical axis 78 overlap in the space between the beam splitter layer 84 and the field 34, respectively.

The limit rays 86 and 88 reaching the first face 90 from the illumination assembly 20 originate from the two outermost cells 50 on opposite sides of the expanded radiation source 22. The central ray 92 reaching the first face 90 from the illumination assembly 20 originates from the central cell 52 of the expanded radiation source 22. All rays 86, 88, and 92 are partially transmitted and partially reflected by the beam splitter layer 84 inside the beam combiner 32, of which only the transmitted rays are shown. In the disclosed embodiment, the rays 86, 88, and 90 exit from the combiner 32 through the second surface 94, wherein the rays 86 and 88 are incident on the field 34 at an angle of incidence exceeding ±55 degrees, and the ray 92 is a method The angle (0 degrees) is incident on the field.

The illumination is scattered (usually reflected and/or diffracted) from the field 34 as rays 96 with an angular distribution that depends on a characteristic on the field. In the depicted example, only their rays 96 within the numerical aperture of the objective optics of the imaging assembly 76 are shown. The rays 96 enter the beam combiner 32 through the second face 94 and are partially reflected and partially transmitted by the beam splitter layer 84, of which only the reflected rays 98 are shown. The reflected rays 98 irradiate the second surface 94, wherein the reflected rays are reflected as rays 100 by total internal reflection (TIR). All in all, the second optical axis 78 is reflected twice in the combiner 32. The ray 100 passes through the third surface 102 and exits from the beam combiner 32 and is received by the imaging assembly 76, which then images the field 34 onto the sensor 79.

Since the rays 86 and 88 irradiate the field 34 with a numerical aperture that exceeds the numerical aperture of the objective optics 77, these rays form dark field illumination, and the ray 92 irradiated on the field with a smaller incident angle forms a bright field illumination. The radiation source controller 23 can control the numerical aperture of the illumination by stimulating different groups 54 of emitters in the expanded radiation source 22, and therefore can select dark field or bright field illumination or both. Additionally or alternatively, the radiation source controller 23 can select a specific azimuth or azimuth range for illumination by only energizing the emitters in the corresponding sector or several sectors.

Second Embodiment FIG. 7 is a schematic cross-sectional illustration of an optical device 120 according to another embodiment of the present invention.

The optical device 120 includes: an illumination assembly 122, an imaging assembly 124, and a beam combiner 134. The illumination assembly 122 includes an expanded radiation source 126, a radiation source controller 128, and a condensing optical device 129. The condensing optical device includes a collimating lens array 130 and a focusing lens 132. The illuminating assembly 122 illuminates a field 136 along a first optical axis 138 through the beam combiner 134. The field 136 with a finite separation (usually 1 mm) from the combiner 134 is formed by an imaging assembly 124 similar in design to the imaging assembly 76 shown above through the combiner (reflected by the surface 152). A second optical axis 140 is used for imaging.

The expanded radiation source 126 includes solid state emitters 142 configured as an array and coupled to the radiation source controller 128, where each solid state emitter is independently excited by the controller. Each emitter 142 radiates at a single wavelength or range of wavelengths that is generally the same for all emitters. In an alternative embodiment, multi-wavelength illumination that can switch between wavelengths or combinations of wavelengths with uniform angle coverage can be achieved by optically combining multiple independently excited solid-state emitters. Same as in) replace each solid-state emitter 142 to implement.

The collimating lens array 130 includes an array of Freinel lenses 144, where each lens is positioned opposite to exactly one solid-state emitter 142, and the lenses are butted together (similar to the lenses of the collimating lens array 27 in FIG. 5). The focusing lens 132 includes a single Freinel lens. In alternative embodiments, lenses other than Freinel lenses may be used, such as lenses with spherical or aspherical surfaces, or any combination of the above.

The combiner 134 includes: a rod with a constant rectangular cross-section along the rod (wherein the term "rectangular" includes a square shape); a first surface 146 facing the condensing optics 129 and close to it; Two sides 148, which face the field 136 and are close to it; and a third side 150, which faces the imaging assembly 124. The beam combiner 134 acts as a homogenizing rod for the spatial distribution of the radiation received through the first surface 146, and it includes a beam splitter coating 152 at a 45 degree angle with respect to its long axis. The concentrating optics 129 focuses the radiation emitted by the expanded radiation source 126 onto the first surface 146, as will be described in detail below. Due to the constant cross-section of the beam combiner 134, the beam combiner preserves the angular direction of the radiation (with a sign change at each reflection).

The radiation emitted by each of the solid-state emitters 142 is received, transmitted, and collimated by a Freinel lens 144 of the collimating lens array 130 facing the specific emitter. For example, radiation emitted from a point 154 on a solid-state emitter 142a, such as ray 156, is transmitted and collimated by a Freinel lens 144a to form ray 158. The focusing lens 132 receives these rays and focuses the rays as rays 160 to a point 162 on the first surface 146, thus imaging the solid-state emitter 142a onto the first surface, which is directed against the light from the illumination assembly 122 The incident surface of the radiation. In the embodiment illustrated in FIG. 7, the point 154 is selected to be positioned at the edge of the solid-state emitter 142a, and the ratio of the focal lengths of the Freinel lens 144 to the focusing lens 132 is selected such that the point 162 (its system point 154 One image) is located at the edge of the first surface 146. The remaining points on the solid-state emitter 142a are also imaged on the first surface 146, between the point 162 and a point 168 on the opposite edge of the first surface 146 (corresponding rays are not shown), so that the image of the solid-state emitter is just filled The first side. Similarly, the images of all other solid-state emitters 142 fill the first surface 146, thus averaging the radiation from all emitters on the first surface. By choosing a different ratio of the focal lengths of the Freinel lens 144 and the focusing lens 132, the image of each solid-state emitter can be caused to overfill the first surface 146.

The analysis of the angular behavior of the lighting on the field 136 can be divided into two parts: first, analyzing the angular behavior of the lighting on the first surface 146, and second, transferring the angular behavior to the field 136.

2 and an analogy between the optical device 120 and the optical device 10 can be used to analyze the angular behavior of the illumination on the first surface 146: the collimator lens array 130 and the focusing lens 132 and the collimator lens array 27 and The focus lens 28 is compared. The solid state emitter 142 is similar to the exit surface 26 and the first surface 146 is similar to the field 34. Furthermore, similar to the telecentric configuration in the optical device 10, the collimator lens array 130 is positioned so that the solid-state emitter 142 is positioned at its focal plane, and the focusing lens 132 is positioned so that the collimator lens array 130 is positioned at its focal plane. .

Therefore, similar to the optical device 10, the lens 144 in the collimator lens array 130 defines the aperture of the illumination assembly 122, and determines the numerical aperture of the illumination cone from each lens 144 to the first surface 146. As in the device 10, the condensing optics 129 is telecentric, and the numerical aperture of the illumination is invariant to translation on the first surface 146. Specifically, in the depicted example, the numerical aperture of the ray cone 160 on the first surface 146 is determined by the lens 144a.

It is now possible to use the ray 160 entering the beam combiner 134 through the first surface to analyze the angular behavior shift from the first surface 146 to the field 136. Although the ray 160 undergoes multiple reflections around the first optical axis 138 in the ray combiner 134, due to the rectangular cross-section of the ray combiner, the ray maintains its angle relative to the first optical axis (at each reflection The place has a sign to change). (For the sake of clarity of the schematic illustration, the refraction of the ray 160 after entering the beam combiner 134 is ignored, and the number of reflections is limited to 2). Continuing similarly to FIG. 2, the rays from all points of the solid-state emitter 142 a fill the same numerical aperture at the first face 146. Since all these rays are transferred to the field 136 by the ray combiner 134, the ray combiner homogenizes its spatial distribution but retains its angular distribution, and therefore spans its lateral extent to the same numerical aperture as the numerical aperture of the ray 160 Illuminate the field.

Similar to the optical device 10, when all the solid-state emitters 142 are activated, by butting the Frenai lens 144 of the collimating lens array 130 together, one of the entire numerical apertures of the illumination of the field 136 can be seamlessly filled.

Conversely, when only some of the solid-state emitters 142 are excited, one of the directional illumination of the field 136 is achieved. For example, if the solid-state emitter 142a is excited, all radiation illuminates the field 136 at a high angle. When this angle exceeds the numerical aperture of the imaging assembly 124, the illumination includes dark field illumination. Similarly, a solid-state emitter 142b located on the first optical axis 138 is excited to produce bright field illumination. Due to the back-and-forth reflections within the combiner 134, excitation of a group of solid-state emitters 142 that are asymmetric with respect to the first optical axis 138 produces illumination with a double angular symmetry on the field 136.

Attributable to the fact that the radiation transmitted from the first surface 146 by the beam combiner 134 is spatially homogeneous and angularly evenly distributed when exiting from the second surface 148, it can be based on the desired irradiance and optics on the field 136 The distance between the second surface 148 and the field 136 is selected for mechanical considerations. For example, this distance can be between 0.5 mm and 2 mm.

Based on the inventor’s simulation, the embodiment of the present invention enables the field 136 to be illuminated with a numerical aperture of more than 0.3 within a diagonal dimension from 2 mm to 20 mm, with a cross-field variation of no more than 10% Irradiance and having a radiant intensity that does not vary more than 20% across the numerical aperture at all points in the field.

The radiation reflected and diffracted by the field 136 returns to the beam combiner 134 through the second surface 148, propagates to the beam splitter coating 152, and is partially reflected and partially transmitted by the coating. The reflected radiation exits through the third face 150 and is received by the imaging assembly 124, which then images the field 136 onto its sensors. The first optical axis 138 and the second optical axis 140 overlap in the space between the beam splitter coating 152 and the field 136, respectively.

Third Embodiment FIG. 8 is a schematic cross-sectional illustration of an optical device 200 according to another embodiment of the present invention.

The optical device 200 includes: an illumination assembly 202, an imaging assembly 204, and an optical combiner 206. The lighting assembly 202 includes an expanded radiation source 208, a spatial light modulator 210, and a collimator lens 212. The collimator lens 212 is used as the condensing optics of the illumination assembly 202, and in a telecentric position, the spatial light modulator 210 (which is the diaphragm of the illumination assembly 202) coincides with its focal plane. In the depicted embodiment, the collimator lens 212 includes a Freinel lens. Alternatively, it may include a conventional high NA lens with a spherical or aspherical surface, or a lens with any combination of Frenet type, spherical and aspherical surfaces. The focal length and diameter of the lens 212 are selected according to the required illumination NA and the desired illuminated field size. A radiation source controller 214 is coupled to the extended radiation source 208 and the spatial light modulator 210.

The illuminating assembly 202 illuminates a field 216 along a plurality of first optical axes 218c through the beam combiner 206, as will be described in detail below. The imaging assembly 204 includes a sensor and objective optics (as shown above) that images the field 216 onto the sensor along a second optical axis 220.

The combiner 206 includes a first surface 222 and a second surface 224 parallel to each other. The beam combiner 206 further includes an inner mirror 226 and a plurality of inner beam splitter layers 228, wherein the mirror and the beam splitter layers are parallel to each other and inclined with respect to the surfaces 222 and 224.

The expanded radiation source 208 emits radiation toward the spatial light modulator 210 along a first optical axis 218 that is divided by reflection in different parts of the optical path between the expanded radiation source 208 and the field 216 The sections marked 218a, 218b, and 218c. The radiation source 208 can be configured similar to a multimedia projector light engine. For example, the light source may include a single white or monochromatic LED, multiple color LEDs or infrared LEDs such as red, green, and blue, one or several lasers, or a laser pump phosphor. Since the multiple beam splitter layers 228 of the beam combiner 206 replicate the illuminated field, it is only necessary that the elongation of the radiation source 208 is high enough to provide the required uniformity in the field illuminated by one of the beam splitter layers 228 Lighting NA. The amplification of the elongation of the luminous combiner 206 is accompanied by a corresponding loss of the radiant intensity of the illumination, which will be explained more fully below. The spatial light modulator 210 controls the spatial distribution of the radiation transmitted and projected toward the collimator lens 212 based on the signal received from the controller 214 (an example is shown in FIG. 9). For example, the spatial light modulator 210 can be a digital micromirror device (DMD), a transmissive liquid crystal (LC) device, or a reflective liquid crystal on silicon (LCOS) device. Alternatively, the SLM may be integrated with the expanded light source 208 and may include a segmented LED source or an organic light emitting diode (OLED) array.

Due to the telecentric design, the collimator lens 212 collimates the radiation from any given point on the spatial light modulator 210, thus forming a collimated ray beam. The angle of the collimated ray beam relative to the first optical axis 218a It is determined by the distance between the predetermined point and the first optical axis and the focal length of the collimator lens 212.

The first optical axis 218a enters into the combiner 206 through the first surface 222, and irradiates the mirror 226. The mirror 226 reflects the first optical axis 218a into a reflected first optical axis 218b. Before reaching the beam splitter layer 228, the reflected first optical axis is subsequently multiplied between the first surface 222 and the second surface 224, respectively. Times reflection. The number of reflections between the first surface and the second surface is determined by the thickness of the combiner 206 and the tilt angle of the mirror 226. When the tilt angle of the mirror 226 is sufficient to allow the radiation to be subsequently reflected from the first surface 222 and the second surface 224 by total internal reflection, and when the beam combiner 206 is sufficiently thin, the beam splitter behaves as a waveguide. In the disclosed embodiment, the combiner 206 is generally from 50 mm to 200 mm long, from 20 mm to 50 mm wide, and from 2 mm to 10 mm thick. The number of internal reflections is usually less than 10, but can be higher. Due to the parallelism of the planes 222 and 224, the ray angle of the radiation propagating in the beam combiner 206 is maintained, and the illumination on the field 216 is telecentric. Since the illumination is telecentric, each spatial position on the spatial light modulator 210 is translated into an angular direction of radiation projected onto the field 216, and by controlling the spatial light modulator, the angular range of the radiation can be selected.

At each beam splitter layer 228, the first optical axis 218b is partially transmissive and partially reflected as one of the reflected optical axis 218c. All optical axes 218c exit through the second surface 224 and illuminate the field 216, thus illuminating the field. The reflectivity of the continuous beam splitter layer 228 is progressive, where the reflectivity increases along the length of the beam splitter 206 so that the reflected flux from each of the layers 228 does not change more than for example One of 10% pre-defined limit. This progression can be achieved for discrete wavelengths by, for example, using thin film interference coatings, where each continuous beam splitter coating is designed to have a desired ratio between reflection and transmission. Suitable thin film coatings can be purchased from, for example, REO Inc. (5505 Airport Blvd, Boulder CO 8030, USA) and IDEX Corporation (200 Dorado Place SE, Albuquerque NM 87123, USA). Although it has a wider wavelength range and stricter uniformity requirements than those expected by the disclosed embodiments, optical coatings with similar functions are manufactured by Lumus (8 Pinchas Sapir Street, Ness Ziona, ISRAEL 7403631) Implemented in the augmented reality optical engine.

Alternatively, the grading can be achieved by a halftone (also known as dot pattern) type coating including metallic dots of varying diameters. The advantage of a dot coating above a dielectric coating is that it is not sensitive to incident wavelength and incident angle. The disadvantage is due to the reduced efficiency of one of the multiple transmissions. The ratio between reflection and transmission can be easily controlled by changing the size of the opaque reflection point relative to the transparent part of the grid. Suitable for beam splitting coating with dots can be, for example, Thorlabs Inc. (56 Sparta Avenue, Newton, New Jersey 07860, USA), Edmund Optics Inc. (101 East Gloucester Pike, Barrington, NJ 08007-1380 USA), Koki Co. Ltd. (1-19-9, Midori, Sumida-ku, Tokyo, 130-0021, JAPAN) and Shimadzu Corporation (1 Nishinokyo Kuwabara-cho, Nakagyo-ku, Kyoto 604-8511, Japan) purchased.

The beam splitter layer 228 is positioned at a distance from the plane of the field 216, usually in the range from 2 mm to 20 mm. Therefore, the distance between 0.15 mm and 0.3 mm of the beam splitter layer 228 is sufficiently small to average out any potential spatial or angular non-uniformity caused by the discrete nature of the dot pattern coating.

Since the illumination on the field 216 is afocal and the image of the SLM 210 is projected to infinity, a section of the combiner 206 enclosed between the extreme edges of the coating 228 constitutes an additional to the illuminated field Limit the aperture. This restricted aperture is schematically represented as an effective aperture 230 through which radiation is directed to the second face 224 of the field. The illumination light from the projected image of the SLM 210 is vignetted by the effective aperture 230 outside the boundary of the field 216.

The disclosed embodiment makes it possible to illuminate the field 216 with a high numerical aperture, only limited by the fact that the propagation of the light within the beam combiner 206 depends on the TIR. In the case of the combiner 206 constructed of glass with a refractive index n<2, the NA of the illumination irradiated on the field 216 is limited to 0.35.

The disclosed embodiment further provides that the irradiance in the field 216 does not vary more than one 10% across the field and has a radiant intensity that does not exceed one 10% across the numerical aperture at all points in the field.

The radiation passing through the illuminating field 216 is backscattered (reflected and diffracted) toward the beam combiner 206, and is transmitted by the beam splitter along the second optical axis 220 into the imaging assembly 204, which then transmits the field 216 Image onto its sensor.

Although it is limited to illuminate NA, the disclosed embodiment has different performance advantages. For example, for a predetermined diagonal size of the illuminated field 216, it achieves an advantageous combination of a relatively large clear lighting balance and a short working distance (refer to the distance between the combinator 206 and the field 216). This combination of features is important, for example, in the high-speed inspection of fine patterns printed or deposited on uneven or flexed electronic substrates.

In addition, as described above, the requirement for reducing the elongation of the lighting assembly 202 through the illumination field is replicated. This change is the low power requirement of the lighting assembly 202 and a smaller size and lower cost of the assembly.

FIG. 9 is a schematic representation of different spatial distributions of the emissivity of radiation from the spatial light modulator 210 of FIG. 8 according to an embodiment of the present invention.

As an example, FIG. 9 shows six different spatial distributions 250, 252, 254, 256, 258, and 260 of the radiation emitted from the spatial light modulator 210. Each distribution includes a central area, such as a central area 262 in the distribution 254, and a ring around the central area, such as a ring 264 in the distribution 254. A white area indicates, for example, a high level of emissivity M of 90%, where 100% refers to the highest possible level of emissivity and 0% refers to zero emissivity. The light shading indicates, for example, the emissivity of a middle level of 50%, and the dark shadow indicates the emissivity of a low level of 10% or less, for example. By suitable combination of the lateral size of the spatial light modulator 210 and the focal length of the collimator lens 212, the boundary between the central area 262 and the ring 264 can be selected to correspond to the objective optics of the imaging assembly 204 Numerical aperture. In this embodiment, the central area 262 corresponds to bright field illumination, and the ring 264 corresponds to dark field illumination. Distributions 250...260 demonstrate different options for the spatial distribution of the emittance from the spatial light modulator 210, which gives different angular distributions of full bright field illumination and dark field illumination at field 216.

Although each of the above-explained embodiments has certain different features, other combinations of these features will be obvious to those skilled in the art after reading this description and are considered to be related to the present invention Within the category. As a non-limiting example, the SLM-based radiation source of the third embodiment above can be used with the optical device of the first or second embodiment, and the emitter arrays of the first and second embodiments can be used with The optical devices of the third embodiment are used together. All such alternative embodiments are considered to be within the scope of the present invention.

Therefore, it will be understood that the embodiments described above are cited by way of examples, and the present invention is not limited to the content specifically shown and described above. Rather, the scope of the present invention includes both combinations and sub-combinations of the various features set forth above, and those who are familiar with the technology will think of these various features after reading the above description and have not been disclosed in the prior art. The changes and modifications.

10: Optical equipment/equipment 20: Illumination assembly 21: Concentrating optics 22: Extended radiation source/source 23: Radiation source controller 24: Homogenizing rod/solid homogenizing rod/rod 25: Incident surface 26: Exit Surface / predetermined exit surface 27: collimating lens array / collimator lens array 28: focusing lens / lens 29: homogenizing rod array / homogenizing rod 30: compensating lens 32: 稜鏡 combiner 34: field 35: first Optical axis 36: ray 38: point 40: ray/collimated ray 42: ray 43: point 50: cell/outermost cell 52: circular central cell/central cell 54: emitter/group 56 : Enlarged Illustration 58: Emitter 60: Emitter 70: Individual collimator lens/corresponding lens/lens/collimator lens/collimator lens/Frene lens segment 72: Circular center lens/lens 76: Imaging Assembly 77: objective optics 78: second optical axis 79: sensor 80: upper beam 82: lower beam 84: beam splitter layer 86: limit ray/ray 88: limit ray/ray 90: first Face/ray 92: central ray/ray 94: second face 96: ray 98: reflected ray 100: ray 102: third face 120: optical equipment 122: lighting assembly 124: imaging assembly 126: extended radiation source 128: Radiation source controller 129: Condensing optics 130: Collimating lens array/collimator lens array 132: Focusing lens 134: Combiner 136: Field 138: First optical axis 140: Second optical axis 142 : Solid-state emitter/emitter 142a: solid-state emitter 142b: solid-state emitter 144: Freinel lens/lens 144a: Freinel lens/lens 146: first surface 148: second surface 150: third surface 152: surface / Beam splitter coating 154: point 156: ray 158: ray 160: ray/ray cone 162: point 168: point 200: optical equipment 202: lighting assembly 204: imaging assembly 206: beam combiner/beam splitter 208: extended radiation source/radiation source/extended light source 210: spatial light modulator 212: collimator lens/lens 214: radiation source controller/controller 216: field 218a: first optical axis 218b: warp Reflective first optical axis/first optical axis 218c: first optical axis/reflected optical axis/optical axis 220: second optical axis 222: first surface/surface 224: second surface/surface 226: internal mirror/mirror 228: beam splitter layer/layer/coating 230: effective aperture 250: spatial distribution/distribution 252: spatial distribution 254: spatial distribution/distribution 256: spatial distribution 258: spatial distribution 260: spatial distribution/distribution 262: central area 264 : Ring 300: point 301: third optical axis 302a: ray/limit ray 302b: ray/central ray 302c: ray/limit ray 303: detail 304a: ray 304b: ray 304c: ray 306a: shot Line 306b: Ray/Refraction Ray/Central Ray 306c: Ray 308: Point/Field Point 310: Point 312a: Ray 312b: Ray/Central Ray 312c: Ray 314a: Ray 314b: Ray 314c: Ray 316a: Ray 316b: Ray /Refracted ray/Central ray 316c: ray 318: point/field point 320: point 400: detail 401: array 402: additional virtual source/virtual source 402a: virtual source 404: virtual extended source/source 406: field lens/flat Convex field lens 408: image 410: ray 412: ray 414: dashed line 416: surface 420: diffuser f _COLL : the distance between the collimating lens and the exit surface / the effective focal length of the collimating lens

Figure 1 is a schematic cross-sectional illustration of an illumination and imaging device according to an embodiment of the present invention; FIG. 2 is a schematic cross-sectional diagram illustrating one of the details of the optical device of FIG. 1 according to an embodiment of the present invention; Fig. 3 is a schematic cross-sectional diagram illustrating one of the details of the optical device according to an alternative embodiment of the present invention; Fig. 4 is a schematic front diagrammatic illustration of a radiation source used in the device of Fig. 1 according to an embodiment of the present invention; Fig. 5 is a schematic front diagrammatic illustration of a collimator lens array used in the device of Fig. 1 according to an embodiment of the present invention; FIG. 6 is a schematic cross-sectional illustration of a combination device used in the device of FIG. 1 according to an embodiment of the present invention; Fig. 7 is a schematic cross-sectional illustration of an optical device according to another embodiment of the present invention; Fig. 8 is a schematic cross-sectional illustration of an optical device according to another embodiment of the present invention; and FIG. 9 is a schematic representation of the different spatial distribution of the emissivity of radiation from a spatial light modulator in the device of FIG. 8 according to an embodiment of the present invention.

10: Optical equipment/equipment

20: Lighting assembly

21: Condensing optics

22: Extended radiation source/source

23: Radiation source controller

24: Homogenizing rod/solid homogenizing rod/rod

25: incident surface

26: Exit surface/established exit surface

27: Collimator lens array/collimator lens array

28: Focusing lens/lens

29: Homogenizing rod array/homogenizing rod

30: Compensation lens

32: 稜鏡 combiner

34: field

35: first optical axis

36: Ray

38: point

40: Ray/Collimated Ray

42: Ray

43: point

70: Individual collimating lens/corresponding lens/lens/collimating lens/collimator lens/frenne lens segment

76: imaging assembly

77: Objective optics

79: Sensor

Claims (58)

An optical device, which includes: A lighting assembly, which includes: Once the extended radiation source, it emits radiation in a controllable spatial distribution; and A telecentric concentrating optical device configured to receive and project the emitted radiation onto a field along a first optical axis with a numerical aperture exceeding 0.3; An imaging assembly including a sensor and objective optics configured to image the field onto the sensor along a second optical axis; and A combiner that is positioned between the field and the condensing optics and the objective optics and is configured to combine the first optical axis and the second optical axis, while making one of the optical axes At least one of them is reflected multiple times in the 稜鏡 combiner. The optical device of claim 1, wherein the condensing optics are configured to uniformly project the radiation in an area of the field having a diagonal size of more than 2 mm, with variations across the area An irradiance of not more than 10% and having a radiant intensity that does not vary more than 20% across the numerical aperture at all points in the region. The optical device of claim 2, wherein the diagonal dimension of the area of the field of the optical radiation in which the condensing optical devices project the optical radiation exceeds 15 mm. The optical device of claim 1, wherein the expanded radiation source includes an emitter array, and the device includes a radiation source controller that is coupled to be selectively excited by the radiation source controller The transmitters control the spatial distribution. The optical device of claim 4, wherein the emitter array includes a plurality of emitters of different respective wavelengths, and wherein the radiation source controller is configured to selectively excite the emitters to control projection to the field One of the spectral content of the radiation above. The optical device of claim 4, wherein the emitter array is a first array, and wherein the light-concentrating optical devices include a second homogenizing rod array, and each rod includes a One or more receive an incident surface of the emitted radiation, and an exit surface through which the radiation is emitted. Such as the optical equipment of claim 6, wherein the condensing optical devices include: A third collimating lens array, wherein each collimating lens is configured to receive and collimate the radiation emitted from each of the homogenizing rods; and A focusing lens positioned to receive the collimated radiation from the third collimating lens array and transmit and focus the radiation onto the field. The optical device of claim 7, wherein the collimating lenses include Freinel lenses. The optical device of claim 7, wherein the focusing lens includes a Freinel lens. Such as the optical device of claim 4, wherein the exit surface of each homogenizing rod includes at least one of a field lens and a diffuser. The optical device of claim 4, wherein the radiation source controller is configured to selectively excite the emitters so as to select an angular range of the radiation projected onto the field. Such as the optical device of claim 11, wherein the angle range is selected from an angle range group consisting of a dark field and a bright field illumination range. Such as the optical device of claim 1, wherein the beam combiner is configured to transmit the first optical axis and reflect the second optical axis twice in the beam combiner. The optical device of claim 13, wherein the second optical axis is reflected from a surface of the combiner adjacent to the field by total internal reflection. The optical device of claim 1, wherein the condensing optical devices include a compensating lens having a meniscus shape close to the combinator. The optical device of claim 1, wherein the beam combiner is configured so that the first optical axis is reflected multiple times in the beam combiner so as to homogenize the radiation projected onto the field. The optical device of claim 16, wherein the first optical axis is reflected from a surface of the combiner facing the imaging assembly by total internal reflection. The optical device of claim 16, wherein the combinator has a rectangular cross-section and includes an incident surface close to the condensing optical devices and an exit surface close to the field, and wherein the condensing optical devices It is configured to focus the radiation emitted by the extended radiation source onto the incident surface. The optical device of claim 18, wherein the expanded radiation source includes an array of emitters, and the concentrating optics are configured to image each of the emitters onto the incident surface. The optical device of claim 19, wherein the condensing optical devices include a Freinel focusing lens. Such as the optical device of claim 1, wherein the extended radiation source includes: A radiation source; and A spatial light modulator configured to receive and selectively transmit the radiation emitted by the radiation source, and The device includes a radiation source controller, which is coupled to control the spatial distribution by driving the spatial light modulator. The optical device of claim 21, wherein the radiation source controller is configured to selectively control the spatial light modulator so as to select an angular range of the radiation projected onto the field. Such as the optical device of claim 21, wherein the spatial light modulator includes a digital micromirror device. The optical device of claim 21, wherein the spatial light modulator includes a liquid crystal device. Such as the equipment of claim 1, in which the combinator includes: An incident surface positioned to receive the radiation projected by the condensing optical devices along the first optical axis; An exit surface, which is close to the field; and A plurality of beam splitter layers within the beam combiner, wherein each of the plurality of beam splitter layers is configured to transmit one of the radiation through the exit surface when transmitting the second optical axis The individual parts reflect onto the field. The optical device of claim 25, wherein the combinator is configured to serve as a waveguide for the projected radiation. The optical device of claim 25, wherein the beam combiner includes parallel to the beam splitter layers and is configured to receive the radiation entering through the incident surface and reflect the received radiation so as to cause the radiation to be at the edge A mirror spreads within the mirror combiner. The optical device of claim 1, wherein the numerical aperture along the first optical axis exceeds 0.5. The optical device of claim 28, wherein the numerical aperture along the first optical axis exceeds 0.7. A method for inspection, which includes: Emit radiation from an extended radiation source in a controllable spatial distribution; Use telecentric concentrating optics to receive and project the emitted radiation onto a field along a first optical axis with a numerical aperture exceeding 0.3; Imaging the field to a sensor along a second optical axis by means of objective optics; and The first optical axis and the second optical axis are combined by using an optical combiner, and the optical combiner causes at least one of the optical axes to be reflected multiple times in the optical combiner. The method of claim 30, wherein projecting the radiation includes uniformly projecting the radiation in a region of the field having a diagonal size exceeding 2 mm, wherein a radiation having a variation of no more than 10% across the region Illumination and having a radiation intensity that does not vary more than 20% across the numerical aperture at all points in the area. The method of claim 31, wherein the diagonal dimension of the area of the field in which the concentrating optical devices project the optical radiation exceeds 15 mm. The method of claim 30, wherein emitting the radiation includes emitting the radiation from an array of emitters, and the spatial distribution is controlled by selectively exciting the emitters. The method of claim 33, wherein the emitter array includes a plurality of emitters of different respective wavelengths, and wherein selectively exciting the emitters includes controlling the projection to the field by selecting the emitters to excite One of the spectral content of the radiation above. The method of claim 33, wherein the emitter array is a first array, and wherein the light-concentrating optical devices include a second homogenizing rod array, and each rod includes one of the emitters positioned Or more receive an incident surface of the emitted radiation, and an exit surface through which the radiation is emitted. Such as the method of claim 35, wherein the concentrating optical devices include: A third collimating lens array, wherein each collimating lens is configured to receive and collimate the radiation emitted from each of the homogenizing rods; and A focusing lens positioned to receive the collimated radiation from the third collimating lens array and transmit and focus the radiation onto the field. The method of claim 36, wherein the collimating lenses include Freinel lenses. The method of claim 36, wherein the focusing lens includes a Freinel lens. Such as the method of claim 33, wherein the exit surface of each homogenizing rod includes at least one of a field lens and a diffuser. The method of claim 33, wherein selectively energizing the emitters includes selecting an angular range of the radiation projected onto the field. Such as the method of claim 40, wherein selecting the angle range includes selecting the range from an angle range group consisting of a dark field and a bright field illumination range. The method according to claim 30, wherein combining the first optical axis and the second optical axis includes transmitting the first optical axis and reflecting the second optical axis twice in the combiner. The method of claim 42, wherein the second optical axis is reflected from a surface of the combiner adjacent to the field by total internal reflection. The method of claim 30, wherein the condensing optical devices include a compensation lens having a meniscus shape close to the beam combiner. The method of claim 30, wherein combining the optical axes includes causing the first optical axis to be reflected multiple times in the beam combiner so as to homogenize the radiation projected onto the field. The method of claim 45, wherein the first optical axis is reflected from a surface of the combiner facing the imaging assembly by total internal reflection. Such as the method of claim 45, wherein the combinator has a rectangular cross-section and includes an incident surface close to the condensing optical devices and an exit surface close to the field, and wherein the condensing optical devices are assembled State to focus the radiation emitted by the extended radiation source onto the incident surface. The method of claim 47, wherein the expanded radiation source includes an array of emitters, and the concentrating optics are configured to image each of the emitters onto the incident surface. The method of claim 48, wherein the condensing optics include a Frenet focusing lens. The method of claim 30, wherein emitting the radiation includes applying a spatial light modulator to control the spatial distribution of the radiation. The method of claim 50, wherein selectively controlling the spatial distribution includes selecting an angular range of the radiation projected onto the field. Such as the method of claim 50, wherein the spatial light modulator includes a digital micromirror device. Such as the method of claim 50, wherein the spatial light modulator includes a liquid crystal device. Such as the method of claim 30, wherein the combinator includes: An incident surface positioned to receive the radiation projected by the condensing optical devices along the first optical axis; An exit surface, which is close to the field; and A plurality of beam splitter layers within the beam combiner, wherein each of the plurality of beam splitter layers is configured to transmit one of the radiation through the exit surface when transmitting the second optical axis The individual parts reflect onto the field. The method of claim 54, wherein the combinator is configured to act as a waveguide for the projected radiation. The method of claim 54, wherein the beam combiner includes parallel to the beam splitter layers and is configured to receive the radiation entering through the incident surface and reflect the received radiation so as to cause the radiation to be in the beam A mirror that spreads within the combiner. The method of claim 30, wherein the numerical aperture along the first optical axis exceeds 0.5. The method of claim 57, wherein the numerical aperture along the first optical axis exceeds 0.7.

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